I saw a gif of this a few years ago and quailed. Yes, I quailed. Not to be confused with kvelled. I just couldn't believe what I was seeing. There is a complete version in the video below, but I am not sure you want to see it. I watched it - the parts of it I could watch - through my splayed fingers.
It soon becomes apparent that the water is not terribly deep, only coming up to the horse's backs, but that poses problems of its own. Trying desperately to gain a footing, the horses flail violently. Broken legs and hypothermia were a dread here, because these horses are small - ponies, really, though accustomed to harsh conditions and thick-coated. This is ice water, however, and they are soaking in it for God knows how long.
I want to tell you, and I WILL tell you, that all of them were rescued, though no one was remotely prepared for this sort of thing. There was much criticism of having this many horses run on the ice at the same time. It's some sort of traditional race held every year, but with global warming - well, never mind. I promised never to write about that again.
The shock and horror of this tiny clip still resonates. It seems like a disaster without a solution, but these horses are plucky and tough. They must have good grips in their hooves, too, or the ice would have proven too much for them.